Storage tanks for transporting fluids using trucks and similar vehicles are preferably mounted to the bed of the vehicle or trailer to avoid capsizing or movement of the tank during transit. In some designs, a number of brackets or flanges are mounted at spaced locations along the base of the tank each formed with one or more bores. The tank is positioned on the bed of the vehicle or trailer, and holes are drilled through the bed to align with the bores in the flanges. The tank is secured to the bed by inserting a carriage bolt from the bottom of the bed through the aligning bore in each flange and the holes drilled in the bed. The threaded end of each bolt, which is exposed above the flanges, receives a rubber or urethane bushing and then a lock nut, such as a nylon-insert lock nut, is tightened down atop the bushing to hold the carriage bolt and tank in place. The resiliency of the bushing is intended to provide a degree of vibration damping between the flanges and bed.
The mounting system described above is readily susceptible to over-tightening. The end of each carriage bolt which extends above the flanges is threaded along its entire length such that the lock nut can be tightened down against the bushing with too much force, resulting in damage to and/or excessive compression of the bushing. When that occurs, the vibration-damping capability of the bushing is reduced or eliminated and the bushing may be damaged.